In recent years, clad metal plates have come to be widely used due to the fact that they take advantage of favorable properties of the base, i.e. backer, metal as well as the cladding material. For example, the corrosion resistance of a titanium base plate can be enhanced by cladding the plate with a reactive metal or metal alloy that exhibits higher corrosion resistance than the base plate.
At present, titanium clad plate composites containing a titanium base plate and a cladding plate may be manufactured by either explosive cladding methods or by encasing the entire composite assembly in an external pack.
The explosive cladding methods employed in the prior art have the drawback that they require at least one soft metal to ensure formation of a sound bond between the backer plate and the cladding plate. Furthermore, these explosive cladding methods are relatively expensive processes, and in some instances a true metallurgical bond between the base plate and the cladding plate may not always be achieved. Accordingly, explosive cladding methods are not cost effective, and thus are not practical for use in bonding a reactive metal or metal alloy cladding to a backer plate that is composed of a reactive metal or metal alloy.
In the prior art, a cladding plate composed of a reactive metal or metal alloy may be bonded to a backer plate by surrounding the entire periphery of the composite assembly in an external pack composed of a metal such as steel. The external pack is first sealed and then the cladding plate is bonded under vacuum to the backer plate. This bonding is conducted under a vacuum to avoid the formation of unwanted surface oxides and/or nitrides at the interface which may cause deterioration of the bond thus formed. The pack assembly is then rolled to a final desired gauge using standard roll milling processes and the external pack is removed and discarded. Although the use of an external pack is feasible in providing a clad plate composite composed of reactive metals, it is not practical since it is too costly and it oftentimes requires the use of expensive parting agents.
Despite the current state in the art there is still a need for improved cost effective processes for producing a composite product that exhibits high corrosion resistant and which contains a stable bond between the backer plate and the cladding plate.